One in three schoolchildren are not taught about sexual consent and what to do "if
something should happen", according to a study

Just four in 10 schoolchildren said they had learned "what is good or bad in a relationship" during sexual education classes at school, the survey of 890 people aged between 14 and 25 found.

Many children surveyed said they had never discussed real-life relationship situations and what to do "should something happen".

A further third did not know where to get help if they were sexually assaulted and 40 per cent did not know how to find their local sexual health clinic, according to the survey by Sex Education Forum, based at children’s charity the National Children’s Bureau.

The study comes as Telegraph Wonder Women campaigns for the Government to update sex and relationship teaching material, last published in 2000 – some 13 years ago – and predating the internet as we know it.

Last year, Nick Clegg, the Deputy Prime Minister, backed the Better Sex Educationcampaign warning that children were being let down by a lack of basic relationships advice and information at school, instead gleaning often distorted and inaccurate information from the internet.

Although the majority of those surveyed by the Sex Education Forum recognised that the legal age of consent is 16, and eight in 10 understood that men could be victims of rape, there is not enough discussion at school on how to 'say no' or the difference between porn and sex.

Currently, there is no official guidance for teachers on how to talk about these difficult subjects to a group of teenagers.

Lucy Emmerson, Sex Education Forum coordinator, who supports the Telegraph's Better Sex Education campaign, said: “We need to listen to the evidence and make high-quality sex and relationships education a guarantee across all schools. This survey confirms that the quality of sex education children receive is a lottery.

"Young people are telling us very clearly that teaching is often too theoretical and fails to deal with the real-life practicalities of getting help and advice or building the skills for pleasurable, equal and safe relationships.

"Learning about consent is integral to good quality sex and relationships education and every school should have a planned programme which includes content on bodily boundaries, gender and power, caring for one another, feelings and emotions and how to get help and advice. ”

Other findings from the survey showed that only a third of young people were aware that a 14-year-old could get contraception confidentially. Less than half of young people were confident that a 15-year-old could get a HIV test without a parent or carer being told and many did not know under-16s can receive confidential contraception.

The Telegraph Wonder Women campaign to bring sex education into the 21st century has been supported by groups and individuals including: the Girl Guides, Claire Perry – the Prime Minister's children’s adviser, Tim Loughton – the Conservative MP and former Children's Minister, Dame Tessa Jowell – the Labour MP, Mumsnet, Professor Tanya Byron, the largest teachers' union – the National Union of Teachers, the National Association of Headteachers, teachers' union NASUWT, the Children's Commissioner – Dr Maggie Atkinson, the PSHE Association, the Sex Education Forum, and the Mother's Union.

Telegraph Wonder Women is campaigning for better sex education, urging David Cameron to bring sex and relationships education into the 21st century. Sign our petition at change.org/bettersexeducation or email us at bettersexeducation@telegraph.co.uk. Follow the campaign on Twitter #bettersexeducation, @TeleWonderWomen